Casio Computer Rebuild Puts New Wine In An Old Bottle

With a glut of vintage consumer electronics available from eBay it should be easy to relive your glory days, right? Unfortunately the march of time means that finding gear is easy but finding gear that works is not. So was the case when [Amen] acquired not one, but two used calculator/computer units hoping to end up with one working device. Instead, he went down the rabbit hole of redesigning his own electronics to drive the Casio QT-1 seen here.

Especially interesting is the prototyping process for the replacement board. [Amen] used a “BluePill” STM32 microcontroller board at its heart, and used point-to-point soldering for the rest of the circuitry on a rectangle of protoyping board. That circuit is non-trivial, needing a 23 V source to drive the original VFD from the computer, a battery-backed real-time-clock (MCP7940), and a GPIO expander to scan the keys on the keypad.

It worked great, but couldn’t be cut down to fit in the case. The solution was a PCB designed to fit the footprint of the original. The modern guts still need more firmware work and a couple of tweaks like nudging that 23 V rail a bit higher to 26 V for better brightness, but the work already warrants a maniacal cry of “It’s Alive!”.

This isn’t [Amen’s] first rodeo. Back in March we looked in on another vintage Casio refurb that sniffed out the display protocol.

Measure 1024 Times, Cut Once

Typically, someone’s first venture into coding doesn’t get a lot of attention. Then again, most people don’t program a CNC table saw right out of the gate. [Jeremy Fielding] wasn’t enticed with “Blink” or “Hello, world,” and took the path less traveled. He tackled I/O, UX, and motion in a single project, which we would equate to climbing K2 as a way to get into hiking. The Python code was over 500 lines, so we feel comfortable calling him an over-achiever.

The project started after he replaced the fence on his saw and wondered if he could automate it, and that was his jumping-on point, but he didn’t stop there. He automated the blade height and angle with stepper motors, so the only feedback is limit switches to keep it from running into itself. The brains are a Raspberry Pi that uses the GPIO for everything. There is a manual mode so he can use the hand cranks to make adjustments like an ordinary saw, but he loses tracking there. His engineering background shines through in his spartan touchscreen application and robust 3D model. The built-in calculator is a nice touch, and pulling the calculations directly to a motion axis field is clever.

We’ve covered [Jeremy]’s DIY dynamometer and look forward to whatever he builds next. Until then, check out a light-duty approach to CNC that cuts foam in two-and-a-half dimensions.

Continue reading “Measure 1024 Times, Cut Once”

Reliving Heathkit’s Glory Days Through A Teardown And Rebuild

In its heyday, the experience offered by the Heath Company was second to none. Every step of the way, from picking something out of the Heathkit catalog to unpacking all the parts to final assembly and testing, putting together a Heathkit project was as good as it got.

Sadly, those days are gone, and the few remaining unbuilt kits are firmly in the unobtanium realm. But that doesn’t mean you can’t tear down and completely rebuild a Heathkit project to get a little taste of what the original experience was like. [Paul Carbone] chose a T-3 Visual-Aural signal tracer, a common enough piece that’s easy to find on eBay at a price mere mortals can afford. His unit was in pretty good shape, especially for something that was probably built in the early 1960s. [Paul] decided that instead of the usual recapping, he’d go all the way and replace every component with fresh ones. That proved easier said than done; things have changed a lot in five decades, and resistors are a lot smaller than they used to be. Finding hookup wire to match the original was also challenging, as was disemboweling some of the electrolytic cans so they could be recapped. The finished product is beautiful, though — even the Magic Eye tube works — and [Paul] reports that the noise level is so low he wasn’t sure if turned it on at first.

We’ve covered the rise and fall of Heathkit, as well as their many attempted comebacks, including an inexplicable solder-free radio and the “world’s most reliable” clock. Looking at these offerings, we think [Paul] may be onto something here.

Rebuilding An Amiga 500 PSU

One of the challenges of keeping a vintage computer up and running is the limited availability of spare parts. While not everything has hit dire levels of availability (not yet, anyway), it goes without saying that getting a replacement part for a 30+ year old computer is a bit harder than hitting up the local electronics store. So the ability to rebuild original hardware with modern components is an excellent skill to cultivate for anyone looking to keep these pieces of computing history alive in the 21st century.

This is in ample evidence over at [Inkoo Vintage Computing], where repairs and upgrades to vintage computers are performed with a nearly religious veneration. Case in point: this detailed blog post about rebuilding a dead Amiga 500 power supply. After receiving the machine as a donation, it was decided to attempt to diagnose and repair the PSU rather than replace it with a newly manufactured one; as much for the challenge as keeping the contemporary hardware in working order.

What was found upon opening the PSU probably won’t come as a huge surprise to the average Hackaday reader: bad electrolytic capacitors. But these things weren’t just bulged, a few had blown and splattered electrolyte all over the PCB. After removing the bad caps, the board was thoroughly inspected and cleaned with isopropyl alcohol.

[Inkoo Vintage Computing] explains that there’s some variations in capacitor values between different revisions of the Amiga PSU, so it’s best to match what your own hardware had rather than just trying to look it up online. These capacitors in particular were so old and badly damaged that even reading the values off of them was tricky, but in the end, matching parts were ordered and installed. A new fuse was put in, and upon powering up the recapped PSU, the voltages at the connector were checked to be within spec before being plugged into the Amiga itself.

As a test, the Amiga 500 was loaded up with some demos to really get the system load up. After an hour, the PSU’s transformer was up to 78°C and the capacitors topped out at 60°C. As these parts are rated for 100°C (up from 85°C for the original parts), everything seemed to be within tolerances and the PSU was deemed safe for extended use.

This sort of repair isn’t exactly rare with hardware this old, and we’ve seen similar work done on a vintage Apple power supply in the past. If you’re less concerned with historical accuracy, [Inkoo Vintage Computing] has also shown off adapting an ATX PSU for use with the Amiga.

Flood Damaged 386 Gets A Modern Rebuild

Until a flood claimed its life, the 386 tower [Tylinol] found on the side of the road served him well as a DOS gaming rig. In the aftermath of the flood, the machine was left with ruined internals and a rusted case; it ended up being tossed in storage where it was slowly rotting away. But a recent idea got him to drag this old dinosaur back out into the light of day and give it a new lease on life with some modern gear.

For our viewing pleasure [Tylinol] documented the restoration of the computer, dubbed SErEndIPITy, from start to finish. The rebuild starts with tearing the machine down to the steel frame and sanding all the rust off. Luckily it looks like no structural damage was done, and a coat of engine enamel got the frame looking more or less like new. The original motherboard mounting solution wouldn’t work for his modern board, so he ended up riveting a piece of sheet metal in and drilling new holes for standoffs to thread into.

A nice element of this rebuild is that [Tylinol] didn’t want to drastically change the outward appearance of the machine. The customary yellowed plastic was left alone, and wherever possible the original hardware was reused. Rather than blow a hole in the case, he took his Dremel to the decorative ribbed design of the front panel and turned it into a stock-looking vent.

The real star of this rebuild is the LED CPU “Speed” display on the front of the case. In its original form, this was a fake display that simply cycled through predefined digits when you pressed the “Turbo” button on the front panel. By grounding them one at a time, [Tylinol] figured out which lines on the PCB controlled each segment of the display and wired it up to a Teensy 3.5. He was then able to write a C# plugin for CoreTemp to display the temperature.

The rebuilt machine is packing an i5-6500 processor, GTX 970 video card, and 8 GB of DDR4 RAM. Not exactly a speed demon compared to some of the modern desktops out there, but it certainly beats the original hardware. Incidentally, so does the Teensy 3.5 controlling the front panel display. There’s a certain irony there…

Cramming modern hardware into the carcass of an outdated computer is nothing new, of course. But we especially like the builds that take the time to make it all look stock.

[via /r/DIY]

Baby Monitor Rebuild Is Also ESP8266 Audio Streaming How-To

[Sven337]’s rebuild of a cheap and terrible baby monitor isn’t super visual, but it has so much more going on than it first seems. It’s also a how-to for streaming audio via UDP over WiFi with a pair of ESP8266 units, and includes a frank sharing of things that went wrong in the process and how they were addressed. [Sven337] even experimented with a couple of different methods for real-time compression of the transmitted audio data, for no other reason than the sake of doing things as well as they can reasonably be done without adding parts or spending extra money.

receiverThe original baby monitor had audio and video but was utterly useless for a number of reasons (French).  The range and quality were terrible, and the audio was full of static and interference that was just as loud as anything the microphone actually picked up from the room. The user is left with two choices: either have white noise constantly coming through the receiver, or be unable to hear your child because you turned the volume down to get rid of the constant static. Our favorite part is the VOX “feature”: if the baby is quiet, it turns off the receiver’s screen; it has no effect whatsoever on the audio! As icing on the cake, the analog 2.4GHz transmitter interferes with the household WiFi when it transmits – which is all the time, because it’s always-on.

Small wonder [Sven337] decided to go the DIY route. Instead of getting dumped in the trash, the unit got rebuilt almost from the ground-up.

Continue reading “Baby Monitor Rebuild Is Also ESP8266 Audio Streaming How-To”

Rebuilding A 1940s TV

TV

There’s a lot of cool stuff to be found under piles of trash in an antique store. [dijt] discovered this when he found a tiny 7″ Motorola television from the 1940s under a stack of trinkets from earlier eras. We can understand [dijt]’s impulse buy, and the trials of rebuilding this ancient TV more than qualifies it as a hack.

If you know where to look, there are hundreds of resources available for old televisions, Hi-Fis, and radio equipment from the dawn of the electrical era to the modern day. After consulting with a few forums, [dijt] got his hands on a schematic for his television set and began work on diagnosing what was wrong with it.

It turned out the original ballast tube in this set had long since given up the ghost. Luckily, this is a common problem in old TVs, and after consulting some forums [dijt] had a schematic to replace this ballast tube with some newer caps and resistors.

After constructing the circuit and testing it out, [dijt] mounted it in the old ballast tube to replicate the original look and feel of the 1949 television. Interestingly, this is the second time this TV had been restored; the 1960s-era caps and resistors told [djit] this TV had once went into a television repair shop. Let’s just hope [djit] remembered to glue the schematics to the inside of the chassis this time.